Propylene glycol is manufactured from glycerin or petroleum. Glycerin is a coproduct that is produced when biodiesel and fatty acids are being made, and propylene glycol can be derived from it. On the other hand, there are ways to get propylene glycol from petroleum as well.
Propylene glycol is also known as 1,2-propanediol or propane-1,2-diol. In science, it is recognized as an organic compound and has the chemical formula C3H8O2. It could be difficult for humans to recognize propylene glycol if they are not familiar with the substance, since it is nearly odorless, colorless, clear, hygroscopic and miscible with acetone, chloroform and water. Its main defining feature is its viscosity, which leaves it denser than water. It is typically used as chemical feedstock for the production of unsaturated polyester resin.
At ADM, their propylene glycol is derived from glycerin. They claim that their propylene glycol meets the same specifications as the propylene glycol that comes from petroleum. The difference is that the glycerin-derived PG is made up of 100 percent biobased carbon content. In traditional manufacturing, it would be normal to see PG made from a petrochemical intermediate with no biobased content, according to ADM.
Functionally, both types of propylene glycol work the same. Their molecular structures are the same, making both types identical chemically.